Soft-tissue neoplasms are not infrequently encountered as one of the clinical manifestations of congenital neurofibromatosis. In those patients in whom diffuse soft-tissue hypertrophy remains relatively isolated and in whom it is limited to a portion of one extremity, radical excision of the hypertrophied subcutaneous tissue and the involved peripheral nerves, when such are encountered, may control the progress of the disease (Figs. 1-A through 3-C). In many patients, however, with a more diffuse type of involvement covering an entire extremity or a greater portion of the body, in whom the deeper soft-tissue structures, as well as the subcutaneous tissue, are involved, regional surgery may not prevent the progression of the process. In many instances, diffuse flat hemangiomatous changes may be encountered and primary or secondary lymphatic involvement may also have occurred. Primary tumors may occur in major nerve structures and these may he benign or malignant in type.